SusChEM: Photochemically-Induced Nucleation and Growth of Manganese Oxides at Environmental Interfaces

在这项由美国国家科学基金会化学部环境化学科学计划资助的项目中，圣路易斯华盛顿大学的Young-Shin Jun教授研究了接触环境时锰化合物的变化。锰的天然丰度是研究其在自然和人为环境过程中的作用的主要动机。许多被锰污染的土地是人类活动(如酸性矿山废水和城市大气污染)造成的。了解各种含锰物种在暴露于环境中的变化对于控制饮用水中的锰浓度至关重要。在华盛顿大学学校合作研究所(ISP)的支持下，Jun教授开发了一系列以“环境化学与能源”为主题的讲座，内容包括实验化学和计算机模拟实验。君教授的研究成果被纳入大学的环境纳米化学和水生化学课程。这些教育活动为本科生和研究生提供了发展机会。这些教育活动由国际科学计划的教员定期进行评估。锰的丰富的氧化还原反应活性在工程系统中很有价值，例如在电池和催化水氧化中。该项目提供了有关锰(Mn)氧化和随后的氧化锰(Delta-MnO2)纳米片状成核和生长的基本热力学和动力学信息。该研究项目利用多学科工具在分子水平上研究增量MnO2纳米片状成核和原位生长的早期阶段。小角X射线散射(SAXS)/掠入射SAXS提供实时信息。用各种X射线技术和电子显微镜研究了矿物相和矿物形态的变化。还进行了流体化学和电化学测试。此外，合成的Delta-MnO2作为锂离子电池中环境友好的有效正极进行了测试。该项目为开发可持续能源材料提供了有用的信息。

In this project funded by the Environmental Chemical Science Program in the Chemistry Division at the National Science Foundation, Professor Young-Shin Jun of Washington University in St. Louis examines changes in manganese compounds on exposure to the environment. The natural abundance of manganese is a primary motivation for studying its roles in natural and man-made environmental processes. Many manganese-contaminated lands result from human activities (e. g., acid mine drainage and contamination from urban atmospheres). Understanding the changes in various manganese-containing species on exposure to the environment is crucial to controlling manganese concentrations in drinking water. With support from Washington University's Institute for School Partnership (ISP), Professor Jun develops an "Environmental Chemistry and Energy" themed lecture series, with experimental chemistry and computer modeling experiments. Professor Jun's research findings are incorporated into university courses in Environmental Nanochemistry and Aquatic Chemistry. These educational activities provide development opportunities for undergraduate and graduate students. The educational activities are evaluated periodically by faculty from the ISP.The rich redox reactivity of manganese is of interest in engineered systems, such as in batteries and catalyzed water oxidation. This project provides fundamental thermodynamic and kinetic information about manganese (Mn) oxidation and subsequent manganese oxide (delta-MnO2) nanosheet nucleation and growth. The research project utilizes multidisciplinary tools to investigate the early stages of delta MnO2 nanosheet nucleation and in situ growth at the molecular scale. Small angle x-ray scattering (SAXS) / grazing incidence SAXS provides real-time information. Changes in mineral phases and mineral morphologies are studied with various X-ray techniques and electron microscopies. Fluid chemistry and electrochemical measurements are also be made. Furthermore, the synthesized delta-MnO2 is tested for its applications as an effective, environmentally-abundant cathode in a lithium-ion battery. This project provides useful information for developing sustainable energy materials.